Abstract
In this study, we consider the automotive gear rattle noise resulting from vibro-impacts that can occur between the unloaded gears under excessive speed fluctuations imposed by the shaft-fixed gears. The main parameters governing such kind of vibrations, are the excitation source related to the engine torque fluctuation which can be modelled by an imposed periodic displacement, the inertia of the free gear, the drag torque acting during the free flight motion and the impact laws. In the case of rattling, it is reasonable to assume that duration of impacts between teeth is very short compared to the free flight duration. Then, impacts can be modelled by a restitution coefficient law. There exists several models for the restitution coefficient, the simplest being a constant one. In fact, it can depend on impact velocity. In this context, this study presents some effects of the restitution coefficient law on the dynamic response of the idle gear.
